垃圾土力学性质的室内试验研究

Experimental studies on mechanical behavior of refuse samples

对室内配制的不同成份的垃圾土分别进行了固结不排水和固结排水三轴压缩试验。结果表明,垃圾土的本构关系基本符合邓肯-张双曲线模型。垃圾土中有机质及土粒的含量是影响垃圾土强度参数 c,φ值的重要因素。对于有机质含量较高而土粒含量较低的垃圾土,c 宜取低值,φ宜取高值。给出了 c,φ值的取值范围及其变化规律。随着时间的变化,c 值会有所增加,而φ值会有所降低。观察到垃圾土的轴向应变超过 30 %而其主应力差仍然在增长。垃圾土在固结过程中,存在滞留孔隙水压力,其渗透系数 k 值的变化与应力、时间、垃圾土的成分等因素有关。在固结排水三轴压缩试验的剪切过程中,孔隙水压力会随轴向应力的增加而增加,试验所得到的总应力强度参数并不就是有效应力强度参数。

The results from the consolidated undrained triaxial compression tests and the consolidated drained triaxial compression tests on the refuses with various compositions, have shown that the constitutive relation of the tested refuse basically fits the Duncan-Chang nonlinear elastic model. The organic and soil contents of refuses are the important factors that affect the strength parameters of refuses. For the refuse with higher organic and lower soil contents, the lower value of cohesion c and higher value of internal friction angle φ should be adopted. The values of c, φ and their variation are given. The values of c will increase and the values of φ will decrease with the variation of time. Although the value of axial strain of refuse exceeds 30%, the phenomenon of the increase of the principal stress difference is observed. The hysteresis pore water pressures in refuse during the consolidation are analyzed. The variation of the seepage coefficients k is related to the stress, time and the composition of the refuse. The pore water pressures of the refuses will increase with the increase of axial stress during the shear of the consolidation drained triaxial compression tests. The total stress strength parameters are not the effective stress strength parameters.